that m1 = 1.1 kg, m2 = 1.7 kg, and m3?
The two blocks (m1 and m2) are attached to a string on a pulley. M3 is hanging off the table by a string that is attached to a pulley. So to be descriptive you have M1 + M2 attached to a string then those two masses attached to M3 through a pulley. Look at this for example: http://www.google.com/imgres?imgurl=http://www.solvephysics.com/ch4_clip_image001_0004.gif&imgrefurl=http://www.solvephysics.com/dch4.htm&usg=__brJnk2xKoLI-9gIgrQplDDolXw4=&h=204&w=268&sz=2&hl=en&start=0&sig2=TTKZQUo4FuRq_N4HgUPi8Q&zoom=0&tbnid=haJcdpCZ-wOzTM:&tbnh=86&tbnw=113&ei=UslcTc3gN4nfgQehmrH6DA&prev=/images%3Fq%3Dtwo%2Bblocks%2Band%2Ba%2Bpulley%26um%3D1%26hl%3Den%26sa%3DN%26biw%3D1280%26bih%3D685%26tbs%3Disch:1&um=1&itbs=1&iact=hc&vpx=1087&vpy=287&dur=3323&hovh=86&hovw=113&tx=80&ty=84&oei=NslcTaOAG4Sclgff3vjlCg&page=1&ndsp=30&ved=1t:429,r:14,s:0
The two blocks (m1 and m2) are attached to a string on a pulley. M3 is hanging off the table by a string that is attached to a pulley. So to be descriptive you have M1 + M2 attached to a string then those two masses attached to M3 through a pulley. Look at this for example: http://www.google.com/imgres?imgurl=http://www.solvephysics.com/ch4_clip_image001_0004.gif&imgrefurl=http://www.solvephysics.com/dch4.htm&usg=__brJnk2xKoLI-9gIgrQplDDolXw4=&h=204&w=268&sz=2&hl=en&start=0&sig2=TTKZQUo4FuRq_N4HgUPi8Q&zoom=0&tbnid=haJcdpCZ-wOzTM:&tbnh=86&tbnw=113&ei=UslcTc3gN4nfgQehmrH6DA&prev=/images%3Fq%3Dtwo%2Bblocks%2Band%2Ba%2Bpulley%26um%3D1%26hl%3Den%26sa%3DN%26biw%3D1280%26bih%3D685%26tbs%3Disch:1&um=1&itbs=1&iact=hc&vpx=1087&vpy=287&dur=3323&hovh=86&hovw=113&tx=80&ty=84&oei=NslcTaOAG4Sclgff3vjlCg&page=1&ndsp=30&ved=1t:429,r:14,s:0